Any which way you add strength you see how it turns out.
I see you did grind off a bit of paint and did weld.
I have for a special alternate use one day my motor bike change gearing from off road trails to parade speed. My motor bike not a charm, but I am as time allows finish up the cover that I can add for parade to look like a California Sheephead Fish.
I mention this as I needed 2 jack shafts so that I geared down to have a slow speed that I could do 5mph and not have to pulse the throttle and heat the clutch. Since the jackshafts are on brackets that are tall and one jackshaft above the other, I did use a clamp method to hold the top and not rely just on the bottom of the brackets. Both ends keep it steady and if I recall I have gearing I can change from the 20:1 to something about twice so I engage the clutch fully at such a slow 5mph.
If I had a manual clutch that would allow it to chug the engine and be more fuel efficient, but that is another build.
top of page post 131 pictures shows a bracket I braced with round tube stock for my training wheel inflatable 10 inch tires so I can go 5mph without worrying about falling over with the parade Fish look.